Abstract

We present the first deep color-magnitude diagram of the Canes Venatici I (CVn I) dwarf galaxy from observations with the wide-field Large Binocular Camera on the Large Binocular Telescope. Reaching down to the main-sequence turnoff of the oldest stars, it reveals a dichotomy in the stellar populations of CVn I: it harbors an old (≳ 10 Gyr), metal-poor ([Fe/H]∼-2.0), and spatially extended population along with a much younger (∼1.4-2.0 Gyr), 0.5 dex more metal-rich, and spatially more concentrated population. These young stars are also offset by 64+40-20 pc to the east of the galaxy center. The data suggest that this young population, which represents ∼3%-5% of the stellar mass of the galaxy within its half-light radius, should be identified with the kinematically cold stellar component found in a recent spectroscopic survey. CVn I therefore follows the behavior of the other remote MW dwarf spheroidals, which all contain intermediate-age and/or young populations: a complex star formation history is possible in extremely low mass galaxies.

title = "A deep large binocular telescope view of the Canes Venatici I dwarf galaxy",

abstract = "We present the first deep color-magnitude diagram of the Canes Venatici I (CVn I) dwarf galaxy from observations with the wide-field Large Binocular Camera on the Large Binocular Telescope. Reaching down to the main-sequence turnoff of the oldest stars, it reveals a dichotomy in the stellar populations of CVn I: it harbors an old (≳ 10 Gyr), metal-poor ([Fe/H]∼-2.0), and spatially extended population along with a much younger (∼1.4-2.0 Gyr), 0.5 dex more metal-rich, and spatially more concentrated population. These young stars are also offset by 64+40-20 pc to the east of the galaxy center. The data suggest that this young population, which represents ∼3%-5% of the stellar mass of the galaxy within its half-light radius, should be identified with the kinematically cold stellar component found in a recent spectroscopic survey. CVn I therefore follows the behavior of the other remote MW dwarf spheroidals, which all contain intermediate-age and/or young populations: a complex star formation history is possible in extremely low mass galaxies.",

T1 - A deep large binocular telescope view of the Canes Venatici I dwarf galaxy

AU - Martin, Nicolas F.

AU - Coleman, Matthew G.

AU - De Jong, Jelte T.A.

AU - Rix, Hans Walter

AU - Bell, Eric F.

AU - Sand, David J.

AU - Hill, John M.

AU - Thompson, David

AU - Burwitz, Vadim

AU - Giallongo, Emanuele

AU - Ragazzoni, Roberto

AU - Diolaiti, Emiliano

AU - Gasparo, Federico

AU - Grazian, Andrea

AU - Pedichini, Fernando

AU - Bechtold, Jill

PY - 2008/1/1

Y1 - 2008/1/1

N2 - We present the first deep color-magnitude diagram of the Canes Venatici I (CVn I) dwarf galaxy from observations with the wide-field Large Binocular Camera on the Large Binocular Telescope. Reaching down to the main-sequence turnoff of the oldest stars, it reveals a dichotomy in the stellar populations of CVn I: it harbors an old (≳ 10 Gyr), metal-poor ([Fe/H]∼-2.0), and spatially extended population along with a much younger (∼1.4-2.0 Gyr), 0.5 dex more metal-rich, and spatially more concentrated population. These young stars are also offset by 64+40-20 pc to the east of the galaxy center. The data suggest that this young population, which represents ∼3%-5% of the stellar mass of the galaxy within its half-light radius, should be identified with the kinematically cold stellar component found in a recent spectroscopic survey. CVn I therefore follows the behavior of the other remote MW dwarf spheroidals, which all contain intermediate-age and/or young populations: a complex star formation history is possible in extremely low mass galaxies.

AB - We present the first deep color-magnitude diagram of the Canes Venatici I (CVn I) dwarf galaxy from observations with the wide-field Large Binocular Camera on the Large Binocular Telescope. Reaching down to the main-sequence turnoff of the oldest stars, it reveals a dichotomy in the stellar populations of CVn I: it harbors an old (≳ 10 Gyr), metal-poor ([Fe/H]∼-2.0), and spatially extended population along with a much younger (∼1.4-2.0 Gyr), 0.5 dex more metal-rich, and spatially more concentrated population. These young stars are also offset by 64+40-20 pc to the east of the galaxy center. The data suggest that this young population, which represents ∼3%-5% of the stellar mass of the galaxy within its half-light radius, should be identified with the kinematically cold stellar component found in a recent spectroscopic survey. CVn I therefore follows the behavior of the other remote MW dwarf spheroidals, which all contain intermediate-age and/or young populations: a complex star formation history is possible in extremely low mass galaxies.